To do this, you have to get an application to run on another desktop. Java will not allow you to capture another desktop without some type of server running on the other desktop.

You will have to set up the application (an applet will not due, because of basic java security) on the other computer and then set up some type of network connection between your controller appliaction and the server set up on the other desktop.... You can use RMI, Sockets, RPC.... whatever...